644 W. A. Drushel — Simple and Mixed Alkyl Phosphates. 



long as any alcohol distilled over. The residue of sodium 

 alcoholate was cooled, covered with absolute ether and treated 

 with the theoretical amount of phosphorus oxychloride, 

 diluted with an equal volume of absolute ether, by adding the 

 diluted phosphorus oxychloride in small portions through a 

 reflux condenser, taking care to keep the reaction mixture 

 cool by immersing the flask in cold water. At the conclusion 

 of the reaction the residue of sodium chloride was filtered off, 

 the fiitrate distilled on a warm water bath to remove the ether, 

 and the residue subjected to fractional distillation. The frac- 

 tionation was made at diminished pressure for all of the esters 

 except trimethyl phosphate, triethyl phosphate and dimethyl- 

 ethyl phosphate. These three esters were distilled at ordinary 

 pressure without decomposition. 



The mixed alkyl phosphates were prepared from the simple 

 esters by making successively the barium salts by the action of 

 aqueous barium hydroxide upon the simple esters at room tem- 

 perature, the free dialkyl phosphoric acids by the action of 

 sulphuric acid upon the purified barium salts, the silver salts 

 of the dialkyl phosphoric acids by the neutralization of these 

 acids with silver oxide, and finally the mixed alkyl phosphates 

 from the silver salts by the action of the appropriate alkyl 

 iodides in ethereal solution. The silver iodide was then filtered 

 off, the ether distilled off from the filtrate and the residue 

 fractionally distilled, generally under diminished pressure. 

 The boiling points of these simple and mixed esters at dimin- 

 ished or ordinary pressure, their densities at 0° and at room 

 temperature and their solubilities in water at room temperature 

 were determined, and are recorded in Table I. According to 

 Winssinger's* observation the tripropyl phosphate decomposes 

 when boiled even in vacuo. In order to test the correctness of 

 this observation this ester was redistilled four times at a pres- 

 sure of I5 mm without any change in the boiling point observed 

 in the first distillation and without any other evidence of the 

 decomposition of the ester. The isobutyl ester was likewise 

 redistilled at 15 mra without any evidence of decomposition. 



In order to determine whether one alkyl group in mixed 

 alkyl phosphates is hydrolyzed to the exclusion of the other 

 alkyl group contrary to the rule in the case of esters of organic 

 acid, the barium salts of a number of simple and mixed alkyl 

 phosphates were prepared by the action of a slight excess of 

 barium hydroxide upon the esters in aqueous solution either at 

 room temperature or upon the steam bath, were purified and 

 analyzed for barium, obtaining the results recorded in Table 

 II. It is to be observed that when barium hydroxide reacts 

 with simple alkyl phosphates the barium content of the result- 

 *Bull. soc. chini., xlviii, 111. 



